1. Field of the Invention
This invention relates to an embroidery data producing apparatus for producing embroidery data necessary for a sewing machine which embroiders a predetermined figure on a work fabric.
2. Description of Related Art
Conventionally, an embroidery sewing machine which automatically embroiders a pattern onto a work fabric is designed to operate in accordance with embroidery data (stitch data or block data). The embroidery data designates needle positions or the like. An embroidery data producing apparatus for automatically producing embroidery data for such an embroidery sewing machine is disclosed, for example, in Japanese Patent Laid-Open Application Nos. Hei 3-33255 and Hei 3-140187.
The embroidery data producing apparatus comprises, for example, an image scanner, a keyboard, a hard disk drive, a CRT (cathode ray tube) display and the like, all connected to a personal computer. An original pattern for an embroidery figure is read by the image scanner to obtain outline data. The outline data defines profiles of embroidery regions of the embroidery figure. From the outline data, block data comprising a plurality of blocks of square or other suitable shape are generated. The block data are obtained by imaginarily dividing each of the embroidery regions. The block data are also continuous in an embroidery proceeding direction. The so-called one-stitch development then produces stitch data designating needle positions.
Of course, some embroidery figures themselves contain another embroidery region. For example, such an embroidery figure A of the head of a person, as shown in FIG. 5, includes a total of eight embroidery regions, R1 to R8, including an embroidery region R1 for the hair portion, an embroidery region R2 for the face portion, a pair of embroidery regions R3 and R4 for the left and right eyebrow portions, a pair of embroidery regions R5 and R6 for the left and right eye portions, an embroidery region R7 for the nose portion, and an embroidery region R8 for the mouth portion. The embroidery regions R3 to R8 are each contained in the embroidery region R2.
When some embroidery regions themselves contain a further embroidery region in this manner, two embroidery forms are available.
According to the first embroidery form, the entire embroidery region containing the additional embroidery regions, referred to as the embroidery-containing region (in the example of FIG. 5, the embroidery-containing region is embroidery region R2 for the face), is filled with stitches. Then, one of the additional embroidery regions contained within the embroidery-containing region, referred to as the contained-embroidery region (in the example of FIG. 5, the embroidery regions R3 to R8 for the eyes, the nose and so forth), is filled with stitches formed over the stitches forming the embroidery-containing region.
According to the second embroidery form, the embroidery-containing region is filled with stitches except for the one or more contained-embroidery regions. Thus, empty contained-embroidery regions are formed within the embroidery-containing region. Then the contained-embroidery region or regions are filled with stitches.
The conventional embroidery data producing apparatus described above uses the first embroidery form to perform overlapping sewing and to produce block data and stitch data in accordance with the method.
However, the conventional embroidery data producing apparatus, where the procedure for producing the embroidery data is fixed as the first embroidery form method, i.e., performing overlapping sewing for embroidery regions having the containing-contained relationship, has the following drawbacks. In particular, since a embroidery-containing region generally covers a large area, embroidery is created with tatami sewing stitches. Tatami sewing denotes a sewing style wherein a sewing distance is too long to be sewn with a single stitch. Consequently, the stitch is sewn with two or more successive stitches along a straight line. Accordingly, the base fabric often becomes so rigid that, upon subsequent embroidery of a contained-embroidery region, the bobbin thread is pulled out to the embroidered surface. Further, since a plurality of stitch layers overlap, a swell is often produced on the embroidery.
Thus, the method of forming empty contained-embroidery regions in the embroidery-containing region according to the second embroidery form is preferred. With this method, however, a gap often forms between the two embroidery regions, caused by dislocation of stitches or by some other cause. The gap deteriorates the appearance of the embroidery. Accordingly, this method cannot be used unconditionally.
Therefore, conventionally, the operator modifies the automatically produced embroidery data (outline data) by hand to form empty contained-embroidery regions. This practice, however, severely burdens the operator and is an obstacle fully automating embroidery data production.